High voltage ignition arrangement for internal combustion engines



Jan. 15, 1963 K. STRAUB 3,073,879

HIGH VOLTAGE IGNITION ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Shoot 1 Filed lay 14, 1962 1963 K STRAUB 3, 73,879.

HIGH VOLTAGE IGNITION ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES Filld lay 14, 1962 2 Shuts-Shut I lNVE/VTOK Mar 6 $61 United States Patent 3,073,879 HIGH VOLTAGE IGNITION ARRANGEMENT FOR INTERNAL COMBUSTION ENGINES Karl Strauh, Stuttgart, Germany, assignor to Robert Bosch G.m.b.H., Stuttgart, Germany Filed May 14, 1962, Ser. No. 194,236 Claims priority, application Germany May 13, 1961 Claims. (Cl. 123-148) The present invention concerns a high voltage ignition arrangement for internal combustion engines, particularly those of automotive vehicles. More particularly the invention concerns an ignition arrangement in which the primary coil of a high voltage ignition coil is supplied with current by a direct current source, and wherein at the moment of the desired ignition the flow of current through the primary coil is interrupted by a transistor connected in circuit with said primary coil. The interruption of the current in the primary coil induces in the secondary coil of the ignition coil a high voltage ignition I ulse. p It has been found desirable to arrange matters so that the magnetic field in the iron core or armature of the ignition coil is built up as completely as possible during the intervals between consecutive ignition pulses so that the interruption of the current flowing through the primary coil generates a strong ignition pulse and spark. Evidently, in the case of high rotary speeds of the engine comparatively little time is available for building up the magnetic field.

It is therefore one object of this invention to provide means for controlling the transistor in such a manner that within a period of conductivity and non-conductivity it remains conductive during a comparatively long period of time and is rendered non-conductive only for a period of time which is a small fraction of the period of conductivity.

It is another object of this invention to provide in an arrangement of the type set forth a pulse generator and circuit means for controlling the transistor in the manner mentioned above.

It is still another object of this invention to provide for an arrangement which is entirely reliable and is yet composed of a comparatively small number of components which are comparatively not expensive and require comparatively small space.

With above objects in mind the invention provides in a high voltage ignition system for internal combustion engines, in combination, an ignition distributor having a shaft operable by the engine; a source of direct current supply; an ignition coil having a primary coil and a secondary coil, the latter furnishing an ignition pulse to said ignition distributor every time when direct current supplied to said primary coil is interrupted; circuit means for supplying said primary coil with direct current and including transistor means having an emitter, a collector and a base, the emitter-collector circuit to said transistor means being connected in series with said primary coil between the terminals of said source, said transistor means permitting, when in conductive condition, direct current to flow through said primary coil, and interrupting said current when rendered non-conductive; voltage divider means including two resistor means connected in series-combination between said terminals of said source, said base of said transistor means being connected with the junction point between said two resistors, a third resistor being arranged between said junction point and said base for applying a potential to the latter whereby said transistor means is rendered conductive; and impulse generator means connected with said base of said transistor means for applying to'the latter intermittently in "ice 2 rhythm with the operation of the engine voltage pulses adapted to render said transistor means nonconductive for brief intervals between comparatively long periods of conductivity.

It has been found particularly advantageous to provide the impulse generator with a rotatable permanent magnet system and with at least one stationary winding means equipped with pole pieces which extend over a comparatively long circular arc and are separated from each other by small gaps extending over only a very small arc, while the rotatable magnet system is equipped with pole pieces having ends facing the pole pieces of the winding means and having a width substantially equal to that of said gaps.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a schematic circuit diagram of an ignition arrangement according to the invention;

FIG. 2 is an elevation, partly in axial section along the line 11-11 of FIG. 3, forming part of the arrangement according to FIG. 1;

FIG. 3 is a transversal section of the generator according to FIG. 2, the section being taken substantially along line.III--III of FIG. 2;

FIG. 4 is a view of one of the magnet pole pieces shown in FIGS. 2 and 3;

- FIG. 5 is a view of one of the pole piece members of the winding means shown in FIGS. 2 and 3;

FIG. 6 is a diagram illustrating the operation of the arrangement according to the invention;

FIG. 7 is a transverse section of a magnet system differing from that illustrated in FIGS. 2 and 3, the section being taken along line VII-VII of FIG. 8;

FIG. 8 is an elevation, partially in axial section along line VIII-VIII, of the magnet system illustrated in FIG. 7;

FIG. 9 is a transverse section taken along line IX-IX of FIG. 10, of another type of magnet system; and

FIG. 10 is an elevation and partial section along line X-X of the magnet system illustrated by FIG. 9.

In accordance with the illustration by FIG. 1, the ignition arrangement according to the invention serving to cooperate with an internal combustion engine not shown comprises a high voltage ignition coil having a primary coil 10 and a secondary coil 12, both being mounted on a common iron core 11. The emitter-collector circuit of a transistor 13 is connected in series with the primary coil 10, the emitter of the transistor 13 being connected to line 14 furnishing positive potential from a source of direct current energy not shown. The other end of the primary coil 10 is connected across a limiting resistor 16 with the corresponding negative line 15 leading to the other terminal of said source. The secondary coil 12 has one of its ends also connected with the negative line 15, while its other end is connected to a high voltage cable 17 with the rotary contact 18 of a conventional ignition distributor 19. Each of the stationary distributor contacts 20 is connected by a corresponding high voltage cable 21 with one of, the four spark plugs of the engine, only one of these spark plugs being symbolically illustrated at 22.

The transistor 13 is so arranged and constructed that in its conductive condition it is capable of carrying a strong magnetizing current through the primary coil 10 which current can be interrupted at the desired moments 3 of ignition for producing inductively an ignition pulse and consequently a spark. In order to hold the transistor 13 normally in conductive condition a voltage divider composed of a resistor 25 of about 2 ohms and a resistor 26 of about 15 ohms is connected between the positive line 14 and the negative line 15-. The base of transistor 13 is connected across a third resistor 27 of about ohms with the junction point between the resistors 25 and 26.

In order to render the transistor 13 non-conductive at the desired moments of ignition a control circuit is provided which includes a permanent magnet type impulse generator 30 described in detail further below and having in this example two windings 31 and 32 connected as shown. The windings 31 and 32 are so connected in the control circuit for the transistor 13 that the windings cannot be energized by current furnished by the above mentioned source of direct current energy. In this manner it is made impossible that the impulses furnished by the impulse generator 30 and serving to render the transistor non-conductive are influenced by the source of direct current energy. For this purpose the two windings 31 and 32 which are subject to induction in opposite directions relative to each other are connected by a common line 33 with a junction point between the resistors 25, 27, on one hand, and the resistor 26, on the other hand. The free outer ends of the windings 31 and 32 are connected with the anodes of two rectifiers 34 and 35. respectively, the cathodes whereof are connected with respective junction points between the base of the transistor 13 and the third resistor 27. As long as the transistor 13 is in conductive condition a voltage is applied to the rectifiers 34 and 35 in a direction opposite to their conductive direction. As can be seen the circuit 33, 31, 34 as well as the circuit 33, 32, 35 are connected in parallel with the third resistor 27. The transistor 13 is rendered nonconductive every time when voltages are induced in the windings 31, 32 in the manner described further below whereby the outer end of the winding 31 or 32 is rendered positive with respect to the potential of line 33. In this case a control current J, is permitted to flow across the respective rectifier and the third resistor 27 whereby the potential at the base of the transistor 13 is made positive with respect to the positive line 14 so that hereby the transistor 13 is rendered non-conductive. When this occurs the magnetic field which has been previously built up in the iron core 11 of the ignition coil by a current flowing through the emitter-collector circuit of transistor 13, the primary coil and resistor 16 collapses on account of the change of the transistor 13 to non-conductive condition whereby an ignition pulse is produced in the secondary winding and transmitted through the ignition distributor 19 to one or the other of the spark plugs 22.

Rcerring now to FIGS. 2-5, a preferred form of an impulse generator will be described which is of particular advantage because it consumes very small space and permits of a structural combination or assembly with the ignition distributor in one common housing so that both units together are easily exchangeable whenever desired.

The assembly according to FIGS. 2 and 3 includes a light metal housing 40 rotatably supporting a hollow shaft 41 which is connected or coupled with the cam shaft of the engine, not shown, and rotating at a speed one-half that of the crank shaft of the engine. The shaft 41 drives, when the engine is in operation, the generator shaft 42 which is turnable within the hollow shaft 41 and connected therewith through a conventional automatic centrifugal adjuster arrangement. The generator shaft 42 carries also a member 43 carrying the distributor contact 18. The automatic adjuster comprises a support plate 45 which is rigidly connected with the hollow shaft 41 at the end of the latter projecting into the housing 40 and carries two pins 46 and 47. To each of these pins is attached one of two coil springs 48, 49, respectively, the other ends thereof being attached to two fly weights 50, 51, respectively, which are coupled with the generator shaft 42 in a well known manner. As the speed of rotation of the engine increases, the fly weights move in radial direction outwardly against the action of the springs 48, 49 and turn accordingly the generator shaft 42 in the direction of rotation of the hollow shaft 41 and relative thereto, the amount of this turning action increasing with increasing speed of the engine.

The impulse generator 30 as illustrated by FIGS. 2-5 comprises in this example a cylindrical permanent magnet 54 which is mounted by means of a brass bushing 53 on the generator shaft 42. The permanent magnet 54 is so magnetized that its magnetic axis coincides with the axis of the shaft 42, its upper end having e.g. N polarity while its lower end has S polarity. The magnet 54 is combined with magnet pole pieces as follows. A pole piece member 55, shown separately in FIG. 4, has a flat central portion mounted on the upper end face of the magnet 54 and is made of soft ferromagnetic material. The ends 56 and 57 of the poie piece are bent downwardly so as to extend in substantially axial direction along the outer surface of the magnet 54, and these end portions 56 and 57 are provided each with a projecting narrow ledge 58, 5), respectively, extending also in axial direction. An identical pole piece member 60 is mounted with its flat central portion on the opposite face of the magnet 54 and has extensions 61 and 62 extending in an opposite direction along the outer surface of the magnet 54 and carrying projecting ledges 63, 64, respectively, in the same manner as described above. As is shown more clearly in FIG. 3, the pole piece members 55 and 60 are offset with respect to each other by an angle of 90.

The stator of the generator is mounted preferably by press fit in the housing 40 as shown and comprises two co-axial ring members 65 and 66 made of soft ferromagnetie material. Of these rings the lower one, marked 66, is shown separately by FIG. 5. The other ring 65 is constructed in exactly the same manner. The ring 66 has two radially and inwardly projecting extensions of which one portion is flat and extends in a plane transvcrsal of the axis while the other portion 68, 69, respectively, extends in axial direction and is curved concentrically with the axis as shown in FIG. 5. The portions 63, 69 constituting the actual winding pole shoes extend over a circular arc subtending a center angle of about so as to face at a small distance the above mentioned projecting ledges 53, 59, 63 and 64 of the magnet system when the latter is in rotation. The upper ring 65, otherwise identical with the ring 66, is mounted in oppositely facing direction on top of the lower ring 66 so that the curved axially extending portions 72 and 73 connected with the ring 65 by radially extending portions 70, 71, respectively, are located concentrically with respect to the above described pole piece portions 68, 69. However, as can be seen from FIG. 3, small gaps are left between the ends of the neighboring pole pieces, for instance between 68 and 73, between 73 and 69 etc. The width of these gaps in circumferential direction is comparatively small and is defined by a circular arc subtending a center angle of about 5. As can be seen from FIGS. 2 and 3 the above mentioned windings 31, 32, each being formed as an annulus, are lodged within the two assembled rings 65 and 66, ore more precisely in the space left between the annular wall of rings 65, 66, respectively, and the respective portions 70, 71, 72, 73, 67, 67', 68, 69.

When the magnet system is in the position shown in FIG. 3 the magnetic flux starting at the N pole of the magnet 54 passes through the upper magnet pole piece 55 and spreads uniformly through the portions 56 and 57 thereof. From the projecting ledge 58 of portion 56 the flux passes through the existing air gap into the opposite pole piece 72, and through the portion 70 into ring 65, from there through substantially contacting edge faces of the ring 65, 66 into the lower ring 66 and spreads from there into the two pole piece portions 68 and 69 from where it returns through the existing air gap and the projecting ledges 63, 64 of the lower magnet pole member 60 to the S pole of the magnet 54.

When now the magnet system rotates from the position illustrated by FIG. 3 in clockwise direction, then the projecting ledge 58 connected with the N pole of magnet 54 assumes a position opposite the pole piece portion 68 of the lower ring 66 while the projecting ledge 63 connected with the S pole of the magnet 54 assumes a position opposite the pole piece portion 72 of the upper ring 65. Consequently, now the direction of the magnetic flux relative to the windings 31, 32 has been reversed. A similar reversal would occur for obvious reasons with each 90 turn of the magnet system.

The above mentioned gaps appearing in circumferential direction between neighboring winding pole pieces 68, 73 or 73, 69 etc. and the width of the projecting ledges 58, 59, 63, 64 of the magnet pole pieces are so chosen that during operation of the engine and of the ignition arrangement according to the invention the magnetic flux passing through the windings 31 and 32 changes substantially as shown in the upper portion of FIG. 6 wherein the alternating positive and negative direction of the magnetic flux is indicated in reference to an abscissa in relation to time t. The magnitude of this magnetic fiux remains practically unchanged as long as the projecting ledges 58, 59, 63, 64 move in the area opposite one of the respective winding pole pieces 68, 73, 69, 72, respectively. However, as soon as these projecting ledges travel past the respective gaps between the winding pole pieces, the flux drops to zero and reaches again a substantially constant value, although of opposite polarity, as the projecting ledges assume positions opposite the next following pair of winding pole pieces. Since the upper portion of FIG. 6 shows that the change of the direction of the magnetic flux from one constant value to a constant value of opposite polarity does not occur instantaneously but requires a small amount of time as indicated by the slanting line portions of the diagram, every change of the magnetic flux from a positive to a negative value induces in the winding 31 a positive voltage impulse U while simultaneously in the winding 32 a similar negative voltage impulse V is induced. At the next following change of the magnetic fiux from negative to positive polarity, after a 90 turn of the magnet system, a similar negative voltage impulse V is induced in the winding 3-1 while in the winding 32 a positive voltage impulse U is induced.

Each of the positive voltage impulses U and U produces a control current I as shown in FIG. 1 whereby the transistor 13 is rendered non-conductive for a brief period of time. However all the above mentioned negative voltage impulses V and V remain inefiective on account of the action of the rectifiers 34 and 35. Therefore the negative pulses have not been illustrated in FIG. 6.

The above mentioned very brief voltage impulses entail the particular advantage that even at very high rotary speeds of the engine and generator operation sufiicient time is available between two consecutive voltage impulses rendering the transistor non-conductive for permitting the electromagnetic field in the iron core 11 of the ignition coil to be built up to its full value. In this manner one is assured that even at very high speeds sufficient ignition energy will be available for each ignition in the secondary coil 12 of the ignition coil.

FIGS. 7 and 8 illustrate a modification of the magnet system of the above described impulse generator. The magnet means of FIGS. 7 and 8 include also two pairs of poles of relatively opposite polarity. The poles are represented by four pole pieces 81 interposed between circumferentially arranged permanent magnet members 82 each having the form of a ring sector. The polarities of the ends of the permanent magnets 82 are so arranged that ends with same polarity abut against one of the pole pieces 81, as shown in FIG. 7. The individual pole pieces 81 project outwardly and have a comparatively narrow outer end face adapted to cooperate with the winding pole pieces of FIGS. 2-5 in the same manner as de scribed above for the projecting ledges 58, 59, 63, 64. The width of the outer end faces of the pole pieces 81 should be substantially equal to that of the above described gaps between the winding pole pieces and may have a magnitude corresponding to a center angle of about 8'. Preferably, the pole pieces 81 and the permanent magnet sectors 82 are assembled with each other to constitute a unit by being embedded in a mass of nonmagnetic material which constitutes an outer shell 83 and an inner hub 84 whereby the magnet sectors 82 are insulated from the generator shaft 42 so that the latter may be made of steel or similar material. The material of the shell 83 and the hub 84 is preferably cast or molded synthetic material. In order to be sure that the pole pieces 81 are firmly held in position in the surrounding shell 83 even at high rotary speeds it is advisable to make the inner end of each of the pieces 81 wider than their outer ends as shown in FIGS. 7 and 8.

FIGS. 9 and 10 illustrate still a further modification of the magnet systems described above. In this case a single integral permanent magnet member is provided which has in this case four arms 91 extending in radial direction as shown in FIG. 9. Each pair of oppositely located arms has the same polarity, but the polarity of the one pair is opposite to that of the other as indicated in FIG. 9. Individual pole pieces 93 made also of soft ferromagnetic material are attached to the outer end faces of the respective permanent magnet arms 91. The pole pieces 93 have each a projecting portion 94 of comparatively narrow width analogous to the arrangements described above. They may have a width corresponding to a center angle of 8 to 10 and are in any case substantially as wide as the above mentioned gaps between the winding pole pieces. Preferably, the individual pole pieces 93 are made up of a plurality of laminations which are held together by a rivet 92. In order to assemble the pole pieces in themselves and with the permanent magnet member 90, holding plates 95, 96 of non-magnetic material may be provided as shown in FIGS. 9 and 10, and these plates may be held together by the above mentioned rivets 92 made also of non-magnetic material. If the center hole of the magnet member 90 corresponds to the outer diameter of the generator shaft 42, then the magnet assembly may be mounted directly on this shaft which however in this case would have to be made of non-magnetic material.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of a high voltage ignition arrangement for internal combustion engines differing from the types described above.

While the invention has been illustrated and described as embodied in a high voltage ignition arrangement for internal combustion engines comprising a control transistor and a control impulse generator, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, 'fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a high voltage ignition system for internal combustion engines, in combination, an ignition distributor having a shaft operable by the engine; a source of direct current supply; an ignition coil having a primary coil and a secondary coil, the latter furnishing an ignition pulse to said ignition distributor every time when direct current supplied to said primary coil is interrupted; circuit means for supplying said primary coil with direct current and including transistor means having an emitter, a collector and a base, the emitter-collector circuit of said transistor means being connected in series with said primary coil between the terminals of said source, said transistor means permitting, when in conductive condition, direct current to fiow through said primary coil, and interrupting said current when rendered non-conductive; voltage divider means including two resistor means conncctcd in series-combination between said terminals of said source, said base of said transistor means being connected with the junction point between said two resistors, a third resistor being arranged between said junction point and said base for applying a potential to the latter whereby said transistor means is rendered conductive; and impulse generator means connected with said base of said transistor means for applying to the la ter intermittently in rhythm with the operation of the engine voltage pulses adapted to render said transistor leans non-conductive for brief intervals between comparatively long periods of conductivi y.

2. In a high voltage ignition system for internal combustion engines, in combination, an ignition distributor having a shaft operable by the engine; a source of direct current supply; an ignition coil having a primary coil and a secondary coil, the latter furnishing an ignition pulse to said ignition distributor every time when direct current supplied to said primary coil is interrupted; circuit means for supplying said primary coil with direct current and including transistor means having an emitter, a collector and a has", the emitter-collector circuit of said transistor means being connected in series with said primary coil between the terminals of said source, said transistor means permitting, when in conductive condition, direct current to flow through said primary coil, and interrupting said current when rendered non-conductive; voltage divider means including two resistor means connectcd in series-combination between said terminals of said source, said base of said transistor means being connected with the junction point between said two resistors, a third resistor being arranged between said junction point and said base for applying a potential to the latter whereby said transistor means is rendered conductive; and impulse generator means connected vith said base of said transistor means for applying to the latter intermittently in rhythm with the operation of the engine voltage pulses adapted to render said transistor means non-conductive for brief intervals between periods of conductivity having a duration at least four times that of said intervals.

3. In a high voltage ignition system for internal combustion engines, in combination, an ignition distributor having a shaft operable by the engine; a source of direct current supply; an ignition coil having a primary coil and a secondary coil, the latter furnishing an ignition pulse to said ignition distributor every time when direct current supplied to said primary coil is interrupted; circuit means for supplying said primary coil with direct current and including transistor means having an emitter, a collector and a base, the emitter-collector circuit of said transistor means being connected in series with said primary coil between the terminals of said source, said transistor means permitting, when in conductive condition, direct current to How through said primary coil, and interrupting said current when rendered non-conductive; voltage divider means including two resistor means connected in series-combination between said terminals of said source, said base of said transistor means being connected with the junction point between said two resistors,

a third resistor being arranged between said junction point and said base for applying a potential to the latter whereby said transistor means is rendered conductive; and impulse generator means connected with said base of said transistor means for applying to the latter intermittently in rhythm with the operation of the engine voltage pulses adapted to render said transistor means non-conductive for brief intervals between periods of conductivity having a duration at least four times that of said intervals, said pulse generator means comprising permanent magnet means and at least one winding means, one of said magnet and winding means being rotatable relative to the other in fixed proportion to the rhythm of the operation of the engine, rectifier means being connected between said winding means and said base for predetermining the polarity of said voltage pulses, said winding means and rectifier means being connected as a series-combination in parallel with said third resistor.

4. An arrangement as claimed in claim 3, including a common housing accommodating said ignition distributor means and said impulse generator means.

5, An arrangement as claimed in claim 4, wherein said permanent magnet means are coupled with said shaft of said ignition distributor for being rotated thereby.

6. In a high voltage ignition system for internal combustion engines, in a combination, an ignition distributor having a shaft operable by the engine; a source of direct current supply; an ignition coil having a primary coil and a secondary coil, the latter furnishing an ignition pulse to said ignition distributor every time when direct current supplied to said primary coil is interrupted; circuit means for supplying said primary coil with direct current and including transistor means having an emitter, a collector and a base, the emitter-collector circuit of said transistor means being connected in series with said primary cell between the terminals of said source, said transistor means permitting, when in conductive condition, direct current to fiow through said primary coil, and interrupting said current when rendered nonconductive; voltage divider means including two resistor means connected in seriescombination between said terminals of said source, said base of said transistor means being connected with the junction point between said two resistors, a third resistor being arranged between said junction point and said base for applying a potential to the latter whereby said transister means is rendered conductive; and impulse generator means connected with said base of said transistor means for applying to the latter intermittently in rhythm with the operation of the engine voltage pulses adapted to render said transistor means non-conductive for brief intervals between periods of conductivity having a duration at least four times that of said intervals, said pulse generator means comprising permanent magnet means and at least one stationary winding means, said magnet means being rotatable relative to said stationary winding means in fixed proportion to the rhythm of the operation of the engine, rectifier means being connected between said winding means and said base for predetermining the polarity of said voltage pulses, said winding means and rectifier means being connected as a series-combination in parallel with said third resistor, said winding means including at least two winding pole pieces each extending along a circular are surrounding said magnet means and subtending a comparatively large first center angle and separated from the other winding pole piece by a gap subtending a second center angle of the order of a small fraction of said first center angle, and said permanent magnet means including at least two magnet pole pieces facing said winding pole pieces and having at their outer ends a width substantially equal to the width of said gaps.

7. An arrangement as claimed in claim 6, wherein said stationary winding means include coil means formed as an annulus concentric with the axis of rotation of said rotatable magnet means, and ring means of soft ferromagnetic material surrounding circumferentially said annulus and having extensions overlapping in radial direction both end faces of said coil means, each of said extensions being formed with a terminal portion projecting into the space surrounded by said coil means and constituting one of said winding pole pieces.

8. An arrangement as claimed in claim 7, wherein said ring means are composed of a first ring member and a second ring member co-axial with each other and facing each other from opposite ends of said said coil means, each of said ring members having at least one of said extensions and terminal portions thereof.

9. An arrangement as claimed in claim 6, wherein said permanent magnet means comprise a number of permanent magnet members. their number corresponding to the number of cylinders in the engine, said permanent magnet members being each formed as a ring segment having opposite polarities at the ends thereof and arranged concentrically with the axis of rotation of said magnet means, magnet pole pieces of soft ferromagnetic material being interposed between said ends of adjacent permanent magnet members have identical polarity, respectively, and each pole piece projecting outwardly with a narrow end ortion extending axially and having a width substantially equal to that of said gaps between said winding pole pieces.

10. An arrangement as claimed in claim 9, wherein said magnet pole pieces are wider at their inner ends than at their outer ends.

ll. An arrangement as claimed in claim 10, wherein said permanent magnet members and said magnet pole pieces are assembled with each other by being embedded jointly in a mass of non-magnetic material.

12. An arrangement is claimed in claim 6, wherein said permanent magnet means comprise a permanent magnet member having a number of radially extending arms, said number corresponding to the number of cylinders in the engine, said arms having in circumferential direction alternating magnetic polarities, respectively, magnet pole pieces made of soft ferromagnetic material being attached to the outer ends of said arms, respectively, and having each an outwardly projecting and axially extending portion of a width substantially equal to that of said gaps between said winding pole pieces.

13. An arrangement as claimed in claim 12, wherein said magnet pole pieces are composed of a plurality of laminations, holding means being provided for holding said laminations together and in contact with said arms.

14. An arrangement as claimed in claim 6, wherein said permanent magnet means comprise a permanent magnet member having its magnetic axis coinciding with the axis of its rotation and a shaft coaxial therewith carrying said permanent magnet member, said magnet pole pieces being made of soft ferromagnetic material and comprising each a first portion mounted on an end face of said permanent magnet member and a second portion extending in substantially axial direction along the outside'of bustion engines, in combination, an ignition distributor having a shaft operable by the engine; a source of direct current supply; an ignition coil having a primary coil and a second coil, the latter furnishing an ignition pulse to said ignition distributor every time when direct current supplied to said primary coil is interrupted; circuit mean for supplying said primary coil with direct current and including transistor means having an emitter, a collector and a base, the emitter-collector circuit of said transistor means being connected in series with said primary coil between the terminals of said source, said transistor means permitting, when in conductive conditiomdircct current to flow through said primary coil, and interrupting said current when rendered non-conductive; voltage divided means including two resistor means connected in series-combination between said terminals of ,said source, said base of said transistor means being connected with the junction point between said two resistors, 21 third resistor being arranged between said junction point and said base for applying a potential to the latter whereby said transistor means is rendered conductive; and impulse generator means connected with said base of said transistor means for applying to the latter intermittently in rhythm with the operation of the engine voltage pulses adapted to render said transistor means non-conductive for brief intcrvals between periods of conductivity having a duration at least four times that of said intervals, said pulse acnerator means comprising permanent magnet means and two stationary Winding means, said magnet means being rotatable relative to said stationary winding means in fixed proportion to the rhythm of the operation of the engine, two rectifier means being connected between said two winding means, respectively, and said base for predetcrmining the polarity of said voltage pulses, each of said winding means and the respectively connected rectifier means being connected as a series-combination in parallel with said third resistor, each of said winding means including two winding pole pieces each extending along a circular arc surrounding said magnet means and subtending a comparatively large first center angle and separated from the other winding pole piece by a gap sub: tending a second center angle of the order of a small function of said first center angle, and said permanent magnet means including at least two magnet pole pieces facing said winding pole pieces and having at their outer ends a width substantially equal to the width of said gaps.

No references cited. 

1. IN A HIGH VOLTAGE IGNITION SYSTEM FOR INTERNAL COMBUSTION ENGINES, IN COMBINATION, AN IGNITION DISTRIBUTOR HAVING A SHAFT OPERABLE BY THE ENGINE; A SOURCE OF DIRECT CURRENT SUPPLY; AN IGNITION COIL HAVING A PRIMARY COIL AND A SECONDARY COIL, THE LATTER FURNISHING AN IGNITION PULSE TO SAID IGNITION DISTRIBUTOR EVERY TIME WHEN DIRECT CURRENT SUPPLIED TO SAID PRIMARY COIL IS INTERRUPTED; CIRCUIT MEANS FOR SUPPLYING SAID PRIMARY COIL WITH DIRECT CURRENT AND INCLUDING TRANSISTOR MEANS HAVING AN EMITTER, A COLLECTOR AND A BASE, THE EMITTER-COLLECTOR CIRCUIT OF SAID TRANSISTOR MEANS BEING CONNECTED IN SERIES WITH SAID PRIMARY COIL BETWEEN THE TERMINALS OF SAID SOURCE, SAID TRANSISTOR MEANS PERMITTING, WHEN IN CONDUCTIVE CONDITION, DIRECT CURRENT TO FLOW THROUGH SAID PRIMARY COIL, AND INTERRUPTING SAID CURRENT WHEN RENDERED NON-CONDUCTIVE; VOLTAGE DIVIDER MEANS INCLUDING TWO RESISTOR MEANS CONNECTED IN SERIES-COMBINATION BETWEEN SAID TERMINALS OF SAID SOURCE, SAID BASE OF SAID TRANSISTOR MEANS BEING CONNECTED WITH THE JUNCTION POINT BETWEEN SAID TWO RESISTORS, A THIRD RESISTOR BEING ARRANGED BETWEEN SAID JUNCTION POINT AND SAID BASE FOR APPLYING A POTENTIAL TO THE LATTER WHEREBY SAID TRANSISTOR MEANS IS RENDERED CONDUCTIVE; AND IMPULSE GENERATOR MEANS CONNECTED WITH SAID BASE OF SAID TRANSISTOR MEANS FOR APPLYING TO THE LATTER INTERMITTENTLY IN RHYTHM WITH THE OPERATION OF THE ENGINE VOLTAGE PULSES ADAPTED TO RENDER SAID TRANSISTOR MEANS NON-CONDUCTIVE FOR BRIEF INTERVALS BETWEEN COMPARATIVELY LONG PERIODS OF CONDUCTIVITY. 